Cooling device

ABSTRACT

A cooling device performance is improved by controlling the cycle of the refrigerant.

This invention relates to a cooling device, the cooling performance ofwhich is improved by controlling the cycle of the refrigerant.

In cooling devices, the circulation of the refrigeration fluid throughunits such as compressor, condenser, capillary tubes and evaporatorconstitutes the cooling cycle. Especially in refrigerators comprisingcooling and freezing compartments, wherein evaporators connected inseries, one for each compartment, are utilized, refrigeration fluidcirculates through the evaporators following their connection order inthe cooling cycle. As a result of this, controlling the coolingtemperatures and efficiencies of the evaporators becomes problematic.

For example, in cooling systems with serially connected evaporators,when there is an instantaneous heat load in a compartment, the systemcan not respond quickly if the evaporator of this compartment is in thelast position in the connection order of the cooling cycle.

Moreover, in cooling systems with serially connected evaporators, sincethe circulation of the refrigerant is in one direction, compartmenttemperatures can not be controlled independently. In such a system, forexample, as the compressor starts operating, refrigeration fluidcirculates through the freezing compartment evaporator first. However,the refrigerant, which was heated up in the stand-by phase fills thefreezing compartment evaporator following the activation of thecompressor. In this transient regime, which starts as the compressorstarts operating and ends as the temperature of the refrigerant reachesto a level suitable for cooling, the temperature of the refrigerantentering the freezing compartment evaporator is too high to be used incooling, so that it may even create a heat load in the compartment.

The object of the present invention is the realization of a coolingdevice, the cooling performance of which is improved by controlling thecycle of the refrigerant.

The cooling device designed to fulfill the object of this invention isillustrated in the attached figures, where:

FIG. 1—is a schematic view of a cooling device.

FIG. 2—is a schematic view of a cooling cycle of the prior art.

FIG. 3—is a schematic view of a cooling cycle.

FIG. 4—is a schematic view of an alternative cooling cycle.

FIG. 5—is a schematic view of an alternative cooling cycle.

Elements shown in figures are numbered as follows:

1. Cooling device

2. Compressor

3. Evaporator

4. Condenser

5. Capillary tube

6. Valve

7. Compartment

8. Control unit

9. Circulation line

10. By-pass line

The cooling device (1), preferably the refrigerator, comprises one ormore than one compartment (7), a compressor (2) which activates therefrigeration cycle, more than one evaporators (3), at least two of thembeing serially-connected, absorbing the thermal energy in the medium tobe cooled, a condenser (4) transferring the thermal energy to the outermedium, a capillary tube (5) enabling the expansion of the refrigerantthat leaves the condenser (4) and transferring it to the evaporator, acirculation line (9) connecting the compressor (2), the evaporator (3),the condenser (4) and the capillary tube (9), more than one valves (6)on the circulation line (9), provided at the inlets or at the outlets ofthe evaporators (3) designating the direction and the order in whichrefrigeration fluid circulates through the evaporators (3), controllingthe circulation during cooling cycle, one or more than one by-pass line(10) connected to at least one valve (6) and connecting to at least oneevaporator (3) directly or by the circulation line (9), enabling therefrigeration fluid directed by the valve to enter the desiredevaporator (3) from the desired direction.

In one embodiment of the present invention, a one way valve (6) isutilized on the cooling cycle (FIG. 3).

In another embodiment of the present invention, two way solenoid valves(6) are utilized in the cooling cycle (FIG. 4).

In another embodiment of the present invention, one way and two wayvalves (6) are utilized in the cooling cycle (FIG. 5).

In yet another embodiment of the present invention, a valve (6)controlling more than one inlets and outlets is utilized in the coolingcycle.

In yet another embodiment of the present invention, the cooling device(1) comprises a control unit (8) controlling the operation of the valves(6).

In the preferred embodiment of the present invention, the cooling device(1) comprises two separate compartments (7), e.g. a cooling and afreezing compartment, two serially connected evaporators (3), one ineach compartment (7) for cooling the compartments (7), e.g. a coolingcompartment evaporator (3) and a freezing compartment evaporator (3), atwo way valve (6) positioned at the inlet of the freezing compartmentevaporator (3) which is the first in the cooling cycle, e.g. a freezingvalve (6), a by-pass line (10) connecting the freezing compartment valve(6) to the cooling compartment evaporator (3) which is positioned afterthe freezing compartment evaporator (6) in the circulation direction,e.g. a freezing by-pass line (10), a two way valve (6) which ispositioned after the connection of the by pass line (10) and the coolingcompartment evaporator (3), e.g. a cooling valve (6), and anotherby-pass line (10) connecting the cooling valve (6) to the inlet of thefreezing compartment evaporator (3), e.g. a cooling by-pass line (10).In this embodiment, when the refrigeration fluid is desired to circulatethrough the freezing compartment evaporator (3) and the coolingcompartment evaporator (3) respectively, e.g. primary circulation (Y),the freezing valve (6) opens the circulation line (9) as it blocks thefreezing by-pass line (10) and the cooling valve (6) opens thecirculation line (9) as it blocks the cooling by-pass line (10). Thus,refrigeration fluid enters and leaves the freezing compartmentevaporator (3) and the cooling compartment evaporator (3) respectivelyand continues its circulation through the circulation line (9). When therefrigeration fluid is desired to circulate through the coolingcompartment evaporator (3) and the freezing compartment evaporator (3)respectively, e.g. secondary circulation (Z), freezing valve (6) blocksthe circulation line (9) as it opens the freezing by-pass line (10) andcooling valve (6) blocks the circulation line (9) as it opens thecooling by-pass line (10). Thus, refrigeration fluid enters and leavesthe freezing by-pass line (10), the cooling compartment evaporator (3),the freezing compartment evaporator (3) and the cooling by-pass line(10) respectively and continues its circulation through the circulationline (9) (FIG. 4).

With the embodiment of the present invention, in a cooling cyclecomprising serially connected evaporators (3), employment of thesecondary circulation (Z) before the primary circulation (Y) starts atransient regime and as the necessary working conditions are provided,system switches to a steady-state regime, wherein the secondarycirculation (Z) is employed after the primary circulation (Y).

As a result of the required positioning of the valves (6), the coolingcompartment (7) evaporator (3) is given the first position and thefreezing compartment (7) evaporator (3) is given the second position inthe cooling cycle, thus freezing compartment (7) evaporator (3) isfilled comparatively later as the compressor (2) starts operating whichin turn provides a suitable cooling during the transient regime.

With the embodiment which is the object of the present invention, theevaporator (3) of the compartment (7) having a temperature higher thanthe ideal level is taken to the first position in the cooling cycle andthus, a better control over the compartment (7) temperatures isachieved.

Since switching between the primary circulation (Y) and the secondarycirculation (Z) in the transient regime, which is achieved by theembodiment of the present invention enables the cooling compartment (7)to be cooled at a relatively higher pressure level, thermodynamicefficiency of the cooling process is improved. At the end of thetransient regime, the refrigeration fluid enters the freezingcompartment (7) evaporator (3) first and this results in an improvementin the efficiency.

Thus, independent of the operation of the compressor, the evaporator (3)of the compartment (7) the heat load of which is increased, is providedto be the first in the cooling cycle by suitable positioning of thevalves (6) and thus, is fed with a more suitable refrigerant.

Moreover, evaporator (3) of the compartment (7) with an instantaneousheat load may be taken to the first position in the cooling cycle. As aresult of the fact that the first evaporator (3) in the cooling cyclehas a better performance, the evaporators (3) of the compartments (7)can cool in different activities and the temperatures of thecompartments (7) may be controlled as required.

The invention claimed is:
 1. A cooling device comprising at least onecompartment, a compressor for activating a cooling cycle, a firstevaporator and a second evaporator connected in series for absorbing thethermal energy available in a medium to be cooled and a circulation linefor connecting units constituting the cooling cycle including, in orderof a refrigerant circulating within the circulation line in a primarycirculation mode, the compressor, a condenser, a capillary tube, atleast one valve, the first evaporator, the second evaporator, and atleast another valve; wherein the at least one valve is connected, via afirst by-pass line and a second by-pass line, to the at least anothervalve, wherein the first by-pass line and the second by-pass line areconnected in parallel to the circulation line with respect to the firstevaporator and the second evaporator, so that the refrigerant flows, ina secondary circulation mode, from the at least one valve through thefirst by-pass line, the second evaporator, the first evaporator and thesecond by-pass line to the at least another valve.
 2. The cooling deviceas in claim 1, further comprising a control unit for controlling theoperation of the at least one valve and the at least another valve. 3.The cooling device as in claim 1, wherein the at least one valve is aone way valve utilized in the cooling cycle.
 4. The cooling device as inclaim 1, wherein the at least one valve is a two way valve utilized inthe cooling cycle.
 5. The cooling device as in claim 4, wherein the atleast one compartment comprises a cooling compartment and a freezingcompartment, and wherein the first evaporator and the second evaporatorare located in the cooling compartment and the freezing compartment,respectively.